Hypnosis and meditation are well known for their health benefits with regards to stress and overcoming bad habits, but recent study found that the alpha state that one achieves with hypnosis can also rejuvenate the mind.

A group of Harvard University students spent eight weeks doing mindfulness mediation as test subjects for a Massachusetts General Hospital study in January of 2011.

The meditating test subjects were examined by Harvard neuroscientists who read MRI scans and found that mindfulness practices change the brain’s gray matter.

“Although the practice of meditation is associated with a sense of peacefulness and physical relaxation, practitioners have long claimed that meditation also provides cognitive and psychological benefits that persist throughout the day,” said Massachusetts General Hospital’s Sara Lazar, who wrote the study.

According to Feelguide magazine, the test subjects would mediate for about a half hour every day. The scientists found that the practice increased the “gray matter density in the hippocampus, the part of the brain associated with self-awareness, compassion, and introspection.”

“This study demonstrates that changes in brain structure may underlie some of these reported improvements and that people are not just feeling better because they are spending time relaxing,” Lazar, who teaches psych at a Harvard Medical School and is part of MassGen’s Psychiatric Neuroimaging Research Program.

The study found that meditation effects how the brain functions even when someone is not actively meditating. Previous neuroimaging studies found that meditation appeared to decrease activation of the amygdala, which helps process memory and emotion. It had been believed that those changes only happened while people were meditating.

“Previous studies from Lazar’s group and others found structural differences between the brains of experienced meditation practitioners and individuals with no history of meditation, observing thickening of the cerebral cortex in areas associated with attention and emotional integration. But those investigations could not document that those differences were actually produced by meditation,” said study co-author Sue McGreevey.

“Participant-reported reductions in stress also were correlated with decreased gray-matter density in the amygdala, which is known to play an important role in anxiety and stress. None of these changes were seen in the control group, indicating that they had not resulted merely from the passage of time,” wrote McGreevey.

“It is fascinating to see the brain’s plasticity and that, by practicing meditation, we can play an active role in changing the brain and can increase our well-being and quality of life,” first author of the paper Britta Hölzel, said.

Hölzel is from the Giessen University in Germany and is a research fellow as Mass Gen.

Meditation and hypnosis use similar relaxation techniques. Meditation quiets the mind. Hypnosis reprograms the mind.